Sigma Art Lens and Dock

[rosko]

2.

[Ilkka Nissilä]

I've never noticed any shift in AF behavior of SWM lenses over time. I guess if there is a real issue of focus miscalibration over time it would be great if Nikon advertised this in the manual in a visible way so that users can take corrective action.

[Akira]

The only disagreement I would report is the lack of AF efficiency in low light, due to the f/4 maximum aperture.

My conclusion : perfect for exterior use, but would need artificial light inside mostly with moving subjects, even if you increase ISO settings. The vibration reduction doesn't compensate as much the lack of brightness.

I would think that is rather a problem on the side of Df which uses now outdated AF module initially introduced on D7000 and used on D600/610.  I loved the image characteristics of D7000 and D610 that I used, but was never really satisfied with the AF performance even with the f1.8 lenses (35/1.8G ED or 50/1.8G).  I never came up with the idea of having my rigs calibrated at Nikon service, though.

[Akira]

I've never noticed any shift in AF behavior of SWM lenses over time. I guess if there is a real issue of focus miscalibration over time it would be great if Nikon advertised this in the manual in a visible way so that users can take corrective action.

That could be a hidden common knowledge among the manufacturers of USM lenses?  Canon also offers the in-camera micro tuning.  I don't know about the Pentax, though.

I briefly used a second-hand Ai-AF Zoom Nikkor ED 70-300/F4-5.6D, the previous model to the current AF-S version.  It had the old screwdrive AF mechanism.  I was totally amazed by its accurate AF on my D750 in entire zoom range at any focusing distances.

[David H. Hartman]

That problem has been solved for quite a long time.  The problem is that the Nikon lenses focuses in the direction that is opposite to most of the lenses of other makes, which drives experienced video/cinema camera operators nuts.  Some follow focus unit can add a small gear to reverse the rotational direction of the focus ring, though.

Nikon and Pentax both adopted the Contax focus direction. I think there are others. I'm not sure why. Someone who knows the history may know. It's very natural to me but then I started serious photograph with a 55/3.5 Micro Nikkor-P on a Nikkormat FTn

If an alternate brand lens company wants to sell me a lens they've got to machine the focus for the correct direction for the camera system the lens is made for.

Dave

[Akira]

Ironically Sigma was the first third party that promote the focus rings turning in the same direction as those of genuine ones.  Today Tokina and Cosina/Zeiss follow Sigma's concept.  Tamron's focus ring still turns in the "reversed" direction in Nikon's term.

Now that I depend mostly on AF    The only occasions I would focus manually don't require quick focusing (closeups of the still subjects or focusing at infinity or at the moon in live view mode), thus I don't care much about the direction anymore.

[David H. Hartman]

I'm glad alternate brand lens makers are adopting the focus direction of camera brand's own lenses. I look at photos to see what direction lenses focus. I note that the Voigtlander APO-Lanthar 125mm f/2.5 focuses as do Nikkors. Unfortunately I was struggling with property tax when I became aware of that lens.

I mostly use AF but I still use manual focus also.

Dave

[pluton]

It is good mental practice to relearn focus direction often, as I do when I operate my Nikon and Fujifilm-X still cameras at home, and then go to work where the Canon and Fujfilm TV Zooms focus in the opposite direction.

[richardHaw]

Pros :
# sharpness;
# nice colour rendition and saturation;
# quiet (equivalent AFS)
# large focal range

cons :
# Huge in size;
# Autofocus needs light;

Below : #1 @ 24mm
             #2 @95mm

Can you please comment on how this thing compares to the Nikon 

[Erik Lund]

The AF error could be a common problem among the lenses using ultrasonic motors.

When I had my AF-S 50/1.8G calibrated at a Nikon service, the tech there told me that the USM would be mis-aligned over time, and then the focusing unit wouldn't stop at the position the camera want.  That leads to the AF error which cannot be fully corrected by the in-camera focus micro-tune function.  You need periodical re-calibration at the service.
,,,

I think this is 'lost in translation' I believe he should have stated: A lens with usm or (swm in Nikon) can become mis-aligned over time,,,

This is what is stated in all of the Nikon repair manuals, if you repair remove and reattach the F-mount or anything similar, you need to recalibrate the lens! All the details are given there if anyone cares to read them,,,

And yes if you want to make sure your lens is at it's top AF performance, you should do maintenance at the Nikon Service.

The ring-motor swm doesn't have a zero position as it has manual override that rotates part of the motor.

In all literature I have seen the same goes for the small-swm with th gearbox design - The repair manual refers to a certain distance the 'drive' has to move the lens croup, not from a zero position,,,

BTW It is believed (by reputable people) that Nikon has incorporated a compensation for focus shift now,,, Could explain why the new G type 1.4 lenses are so damn good at nailing focus,,,

[Pistnbroke]

Spoke to sigma ...
Should work out the box ..slight FFA on camera may help
Should work with any Nikon (if you have more than one body) slight FFA for each body may be required.
Moving the focus point around the screen should be fine.
Warrantee only applies to european lenses and original purchaser.
Its going back as its not working for whatever reason /dropped/fiddled with on a dock.
Thanks everyone for there help.

[Akira]

I think this is 'lost in translation' I believe he should have stated: A lens with usm or (swm in Nikon) can become mis-aligned over time,,,

This is what is stated in all of the Nikon repair manuals, if you repair remove and reattach the F-mount or anything similar, you need to recalibrate the lens! All the details are given there if anyone cares to read them,,,

And yes if you want to make sure your lens is at it's top AF performance, you should do maintenance at the Nikon Service.

The ring-motor swm doesn't have a zero position as it has manual override that rotates part of the motor.

In all literature I have seen the same goes for the small-swm with th gearbox design - The repair manual refers to a certain distance the 'drive' has to move the lens croup, not from a zero position,,,

BTW It is believed (by reputable people) that Nikon has incorporated a compensation for focus shift now,,, Could explain why the new G type 1.4 lenses are so damn good at nailing focus,,,

Erik, you are right.  Sorry for the confusion, and thanks for the detailed follow-up!

[rosko]

Can you please comment on how this thing compares to the Nikon 

Not easy, as I never used a similar Nikon one. The closest would be the Nikkor 24-120mm which the 2 first versions were reputed as from ''crap'' to ''not-so-good'', the last one ( ED version) it said to be very sharp but it's much more expensive.

I got the Sigma second hand in pristine condition for a decent price. I, of course, tried it before purchase (the enlarging function of the live-view helps ), as I was aware of this recurrent problem of front/back focus.

I had used few years the macro 150mm f/28, so I was already convinced about Sigma lenses sharpness.

[PeterN]

Everything worked extremely well until I brought in the D750 for shutter replacement. Now it's off.